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Divulga\u00e7\u00e3o ABC<\/span><\/a> Jayme TiomnoDivulga\u00e7\u00e3o ABC<\/span><\/p><\/div>\n It was there that he did some of his most important work: he proposed the universality of Fermi interaction, now known as the weak interaction\u2014the force that governs interaction among particles in an atom\u2019s nucleus.<\/p>\n In the late 1940s, a decades-long belief that there was no more to an atom than three particles\u2014neutrons, protons, and electrons\u2014had been challenged by experiments with cosmic rays that revealed other elementary particles with different masses, charges, and properties. Three types of decay were now known: the first was beta decay, consisting of the breakdown of a neutron and proton respectively into a proton, electron, and antineutrino, and into a neutron, positron, and electron neutrino; the second involved the decay of pions\u2014particles with a mean lifetime of 26 nanoseconds, codiscovered by fellow Brazilian physicist C\u00e9sar Lattes (1924\u20132005)\u2014into muons and muon neutrinos; and the third was the decay of a particle with a mass 200 times greater than that of the electron\u2014the muon\u2014into an electron, an electron neutrino, and a muon neutrino.<\/p>\n \u201cAt that time,\u201d explains physicist Ignacio Bediaga, of the Brazilian Center for Physics Research (CBPF), \u201cthe three types of decay were thought to be independent phenomena, with different origins.\u201d Tiomno proposed unifying the three reactions in the atom\u2019s nucleus and demonstrated mathematically that they resulted from interactions with the weak force, mediated\u2014as would be experimentally demonstrated only in 1983\u2014by charged W boson particles. The proposed universality of weak interactions was illustrated through a diagram, known as the Tiomno-Wheeler triangle, in a 1949 article in Reviews of Modern Physics<\/em>, giving visual substance to what was then a novel idea.<\/p>\n Jayme Tiomno Archives<\/span><\/a> Jayme Tiomno in his room at Princeton, in 1948Jayme Tiomno Archives<\/span><\/p><\/div>\n \u201cThe triangle synthesized what was then the state of the art of particle physics and is now a well-established concept,\u201d says physicist and historian of science Olival Freire Junior, of the Federal University of Bahia (UFBA). Years later, when authorship of the diagram was lost to another scientist, Wheeler complained and attempted to set the record straight for his former student.<\/p>\n Italian physicist Giorgio Salvini (1920\u20132015) recalled those days at Princeton in 1993 when he visited CBPF and asked Bediaga, who had done his doctorate in Italy, to arrange for him to speak to Tiomno. He was unable to, as his former colleague was ill. \u201cHe was the only one kind enough to complete his exercises in 15 minutes and then pass them on to us to copy, unlike like our American classmates,\u201d says Salvini, who served as Minister of Science in Italy from 1995 to 1996.<\/p>\n Jayme Tiomno Archives<\/span><\/a> A diagram drawn by Wheeler in 1949 to illustrate how he and Tiomno had unified the transformations between three pairs of particles: neutron and proton (N and P); electron (e) and electron neutrino (v); and negative muon (\u03bc) and muon neutrino (\u03bc0<\/sub>)Jayme Tiomno Archives<\/span><\/p><\/div>\n At CBPF<\/strong> In 1952 he joined Elisa, now his wife, at CBPF, a research center created two years prior with his support. In an interview he gave in 1977 to researchers at Funda\u00e7\u00e3o Getulio Vargas, when he also recounted his memorable flight to the US, Tiomno recalled how CBPF had been created because, \u201cother than in S\u00e3o Paulo, all Brazilian universities made it as difficult as possible to do research,\u201d especially for those who had studied abroad.<\/p>\n Jayme Tiomno Archives<\/span><\/a> At Princeton, in 1949: C\u00e9sar Lattes, Hideki Yukawa, and Walter Schutzer (standing, left to right<\/em>); Herv\u00e1sio de Carvalho, Jos\u00e9 Leite Lopes, and Jayme Tiomno (squatting<\/em>)Jayme Tiomno Archives<\/span><\/p><\/div>\n During his time at CBPF, Tiomno explored another idea in his doctoral thesis: a mathematical equation that could explain weak interactions. He selected one of two possible approaches, but it was the one he left aside that would later prove consistent with experiments using particle accelerators. In 2003, Freire heard Tiomno admit that he had neglected to consider research into pion decay that had been done by Elisa and physicist Neusa Margem at CBPF, which would have shown that the second mathematical approach was the right one. \u201cHe chose to use more recent findings from another researcher, but which ultimately proved wrong,\u201d says science historian Alfredo Tolmasquim of the Museum of Tomorrow, in Rio de Janeiro. Tolmasquim, who is Tiomno\u2019s nephew, hopes to publish a biography titled Jayme Tiomno: A life for physics, a life for Brazil<\/em> (Springer) in June, coauthored with German physicist William Brewer, a retired researcher at the Free University of Berlin who lived for 10 years with Tiomno\u2019s stepdaughter, S\u00f4nia.<\/p>\n \u201cTiomno is part of a generation of Brazilian researchers\u2014including Lattes, Schenberg, and Leite Lopes\u2014who collaborated with the world\u2019s greatest scientists and established a scientific approach that made Brazilian physics research world class,\u201d says Bediaga, who coauthored five scientific articles with Tiomno. \u201cHe encouraged his students to try new and bold ideas, and then to work hard to pursue them.\u201d<\/p>\n Jayme Tiomno Archives<\/span><\/a> Tiomno receiving a Moinho Santista award in 1957Jayme Tiomno Archives<\/span><\/p><\/div>\n In 1960, at a conference on high-energy physics in the US, Tiomno proposed a new type of meson resulting from the decay of another particle, the baryon. This was the first study on the transformation of a particle into other more stable particles, known as resonance. Soon after, the K* (890) vector meson, with a mass close to what he had suggested, was discovered in an experiment using an accelerator at the University of California at Berkeley. But the particle proposed by Tiomno would be closer to the kappa (800) meson, identified in 2002, says Bediaga.<\/p>\n Back to Princeton<\/strong>
\nAfter returning to Brazil in 1950, Tiomno worked as a research assistant at USP and became reacquainted with experimental physicist Elisa Frota Pessoa (n\u00e9e<\/em> Elisa Esther Habbema de Maia, 1921\u20132018). Elisa, whom he would later marry, was then married to biologist Oswaldo Frota Pessoa (1917\u20132010). After 18 months, he resigned from USP to return to Rio, where he worked as a part-time professor at the National School of Philosophy.<\/p>\n
\nIn 1965 Tiomno moved to the University of Bras\u00edlia (UnB), but soon resigned along with more than 220 professors who refused to accept the military government\u2019s intervention in universities, spending a year at the International Center for Theoretical Physics, in Trieste, Italy. In 1968, after returning to Brazil and taking a post at USP, he and Elisa were included in a list of university professors deemed to be leftist sympathizers. The following year, with the promulgation of Institutional Act No. 5, they were ousted from the university with many other professors, including Schenberg and Leite Lopes and sociologists Florestan Fernandes (1920\u20131995) and Fernando Henrique Cardoso.<\/p>\n